This study was designed to determine the natural history of diabetic renal transplant candidates with varying degrees of coronary artery stenosis, and evaluate efficacy of coronary revascularization in a subset of patients in a randomized controlled trial. Diabetic renal transplant recipients have a dramatically shorter survival than do nondiabetic transplant recipients, and the major cause of death is coronary artery disease. Many transplant centers are reluctant to transplant diabetics with severe coronary artery disease because of their uncertain prognosis. In this study, 178 consecutive insulin dependent diabetic patients have undergone coronary angiography prior to renal transplantation, and 122 additional patients will be recruited. All patients undergo a detailed baseline evaluation including coronary angiography. Angiograms are evaluated by two independent readers. Patients with one or more coronary artery stenoses greater than 75% are advised to have angioplasty or bypass surgery. As part of this study, twenty six patients with one or more coronary stenoses greater than 75% were randomized to medical treatment vs revascularization. An excess number of cardiac endpoints in the medically treated patients prompted the recommendation of revascularization to all patients with one or more coronary artery stenoses >75%. Patients have yearly followup and interim hospital records are reviewed to determine whether the predetermined study endpoints of unstable angina, myocardial infarction or cardiac death have been reached. Potential risk factors for coronary atherosclerosis are measured at baseline, followed prospectively, and correlated with angiogram data. These include blood pressure, smoking habits, and serum levels of lipids, fibrinogen, lipoprotein(a) Lp(a)), hemoglobin A1C, creatinine, and low density lipoprotein (LDL) resistance to oxidation. The major objectives of this study are to (1) evaluate cardiovascular disease as a contributor to morbidity and mortality in diabetic renal transplant recipients (2) to determine risk factors for coronary atherosclerosis in this population (3) to evaluate the effect of transplantation on specific risk factors including Lp(a), fibrinogen and LDL resistance to oxidation (4) to determine potentially modifiable risk factors for cardiac events after transplantation in patients with established coronary artery atherosclerosis.